-----------------------------------------------------

     =========================================================
     Geant4 - an Object-Oriented Toolkit for Simulation in HEP
     =========================================================

                            electronScattering   
                            ------------------

 Electron scattering benchmark (T. O'Shea and B. Faddegon)
 - J. Ramos-Mendez Updated physics list 
 - J. Ramos-Mendez Fixed spikes produced by scattered e- at cosTheta = 0
 - J. Ramos-Mendez Added analysis.py. It depends on root software and python
	
 1- GEOMETRY DEFINITION
 
 The geometry is described in the enclosed documument : NRCC_electron_scat.pdf
    
 A "World" volume contains a "Frame" made of Air. 
 The Frame contains : ExitWindow, ScatterFoil, MonitorChbr, Bag.
 The Bag contains a Gas volume, which contains 2 aluminium Rings
 The Scoring plane is the end-plane of the Frame
 	
 The default geometry is constructed in DetectorConstruction class.
 The parameters of the ScatterFoil (material and thickness) must be defined
 via 2 UI commands : see the macro scatter.mac
 
 2- PHYSICS LIST
 
 Physics lists can be local (eg. in this example) or from G4 kernel
 physics_lists subdirectory.
     
 Local physics lists:	 
 - "local"	standard EM physics with current 'best' options setting.
                these options are explicited in PhysListEmStandard
 - "standardSS" standard EM physics with single Coulomb scattering 
                instead of multiple scattering			
    
 From geant4/source/physics_lists/builders:	 
 - "emstandard_opt0"  recommended standard EM physics for LHC
 - "emstandard_opt1"  best CPU performance standard physics for LHC
 - "emstandard_opt2"  alternative models    
 - "emstandard_opt3"  current state of art for EM physics
                      analog to "local"above
    
 Physics lists and options can be (re)set with UI commands
    
 Please, notice that options set through G4EmProcessOPtions are global, eg
 for all particle types. In G4 builders, it is shown how to set options per
 particle type.

         	
 3- PRIMARY GENERATOR : mono-enegetic pencil beam
 
 The primary kinematic consists of a single particle which hits the detector 
 perpendicular to the input face (ExitWindow). The type of the particle and its
 energy are set in the PrimaryGeneratorAction class, and can be changed via 
 the G4 build-in commands of ParticleGun class. 
 (see the macros provided with this example)
	
 The incident beam has a Gaussian-shaped spatial distribution. The rms of the 
 Gaussian can be define with an UI command built in PrimaryGeneratorMessenger.
 
 4- VISUALIZATION
 
 The Visualization Manager is set in the main().
 The initialisation of the drawing is done via the commands in vis.mac
 In interactive session:
 PreInit or Idle > /control/execute vis.mac
 	
 The example has a default view which is a longitudinal view of the detector.
 	
 The tracks are drawn at the end of event, and erased at the end of run.
 Optionaly one can choose to draw all particles, only the charged, or none.
 This command is defined in EventActionMessenger class.
 
 5- TRACKING
 
 One can  limit 'by hand' the step lenght of the particle. As an example,
 this limitation is implemented as a 'full' process : see StepMax class and its
 Messenger. The 'StepMax process' is registered in the Physics List. 
  	
 6- DETECTOR RESPONSE
  	
 At the end of a run, from the histogram(s), one can study different
 physics quantities, via the histograms defined below.
 
 An ascii file corresponding to histo 4 (see below) is automatically written.

 
 7- List of the built-in histograms
 ----------------------------------
        
 The test contains 4 built-in 1D histograms, which are managed by
 G4AnalysisManager class and its Messenger. The histos can be individually activated
 with the command :
 /analysis/h1/set id nbBins  valMin valMax unit 
 where unit is the desired unit for the histo (MeV or keV, deg or mrad, etc..)
 (see the macros xxxx.mac).
 
	1	"(charged particles): projected angle at Scoring plane"
	2	"(charged particles): dN/dS at Scoring plane"
	3	"(charged particles): d(N/cost)/dS at Scoring plane"
	4	"(charged particles): normalized d(N/cost)/dS at Scoring plane"
        5       "(charged particles); scattering angle theta"
        6       "(charged particles); measured scattering angle theta"

 The histograms can be viewed using ROOT or PAW.
 
 One can control the name and format of the histograms file with the command:
 /analysis/setFileName  name  (default nrccBenchmark) 
 It is possible to choose the format of the histogram file : root (default),
 xml, csv, by using namespace in HistoManager.hh   
 It is also possible to print selected histograms on an ascii file:
 /analysis/h1/setAscii id
 All selected histos will be written on a file name.ascii (default nrccBenchmark)

	
 8- HOW TO START ?
 
 - execute electronScattering in 'batch' mode from macro files e.g.
 	% electronScattering   myMacro.mac
		
 - execute electronScattering in 'interactive' mode with visualization e.g.
 	% electronScattering
	Then type your commands, for instance :
	Idle> control/execute vis.mac
	Idle> run/beamOn 5
	....